My experience with bittorrent is that it's WAY too slow when there are fewer than half a dozen other people, and that describes too many map transfer situations. Of course, I know nothing of the technical side of that. Certainly it merits a fair evaluation, as in any lobby there is at least one seed and several other potential peers.

The thing is, BitTorrent with fewer than half a dozen uploaders is still faster than just one uploader. BitTorrent is the ideal distribution system for this situation, especially if you use super-seeding (the seed will only upload pieces no other peers have) when there is only one complete seed.